[gmx-users] Building full GROMACS and mdrun only with MPI and GPU: FFTW and regression tests

[João M. Damas]

Hi all,

I am trying to build GROMACS in a similar fashion to what is described in
section 2.3.5 of the manual (weblink
<http://manual.gromacs.org/documentation/2019.5/install-guide/index.html#testing-gromacs-for-correctness>),
i.e. a full build of GROMACS without any particular flags, and then a build
of mdrun only, with MPI and GPU enabled.

My first issue would be with the compilation of the FFT library, namely the
recommended FFTW through -DGMX_BUILD_OWN_FFTW=ON. I find that flag very
useful, but with a recipe as described in section 2.3.5, it would mean
compiling FFTW twice, which is a waste of time. Do you recommend for me to
compile FFTW separately on my own or is there a way/flag to pass the
compiled static library to the mdrun building step?

My second issue is with the regression tests. Using the procedure of
section 2.3.5, with a mdrun building recipe like this:

cmake3 .. \
       -DCMAKE_INSTALL_PREFIX=${SOFTWARE_INSTALL_PREFIX} \
       -DGMX_BUILD_OWN_FFTW=ON \
       -DGMX_DEFAULT_SUFFIX=OFF \
       -DGMX_BINARY_SUFFIX=_mpi \
       -DGMX_LIBS_SUFFIX=_mpi \
       -DGMX_MPI=ON \
       -DGMX_GPU=ON \
       -DGMX_BUILD_MDRUN_ONLY=ON
make -j ${NPROCS}
make install

there are issues with running `./gmxtest.pl all -np ${NPROCS} -mdrun
mdrun_mpi`. Since I am using the same install prefix for both building
steps, I am using the suffix flags stated, but then I need to fix
gmxtest.pl (namely
change the autosuffix variable from 1 to null) to make the tests run
(succesfully). Am I doing something wrong with the suffixes? I believe I
need them if I want to install on the same prefix.

Finally, is there a better way of doing this process to achieve the same
result (i.e. a full build of GROMACS without any particular flags, and then
a build of mdrun only, with MPI and GPU enabled)? In the case that section
is outdated.

Thank you in advance,
João